Recently, as an insufficient supply of oil is gradually real, it is expected that the price of oil is increased. Further, in order to prevent global warming, efforts to reduce CO2 emissions is accelerating internationally.
Therefore, technical development for minimizing a loss of electric power and an environmental problem in an LED lighting apparatus has been continued. Until now, SMPS (Switching Mode Power Supply) is generally applied to the LED lighting apparatus.
In an LED lighting apparatus having the SMPS, since high capacity condenser and transformer are used in the SMPS, an electric power loss of at least 15% or more occurs according to power conversion. That is, since the LED lighting apparatus having the SMPS coverts commercial power into DC voltage, and then uses the DC voltage as a driving voltage, the power efficiency is deteriorated. Further, it is necessary to establish countermeasures against noise such as EMI (Electro-Magnetic Interference) generated by switching.
Furthermore, in LED lighting apparatus having the SMPS, it is difficult to achieve microminiaturization and IC integration thereof due to the high capacity condenser and transformer, and it causes high manufacturing cost.
Meanwhile, FIG. 8 shows the principle of generating a DC voltage using a general full-wave rectifier circuit, and FIG. 9 shows wave forms of current and commercial power supplied to the full-wave rectifier circuit of FIG. 8.
A rectifier circuit part 610 is to full-wave rectify the commercial power, and comprised of a diode D62 612, a diode D64 614, a diode D66 616 and a diode D68 618.
A DC voltage generating part 620 is to drive a circuit of the LED lighting apparatus, and comprised of a resistor R62 622, a zener diode ZD62 624, a condenser C62 626 and a condenser C64 628.
The commercial power shown in FIG. 9a is supplied to the rectifier circuit part 610. In case that a rated voltage of the zener diode ZD62 624 is 6V, a voltage Vcc generated from the DC voltage generating part 620 is 6V due to the rated voltage of the zener diode ZD62 624. Meanwhile, when the commercial power shown in FIG. 9a is supplied to the rectifier circuit part 610, a value of current flowing through the resistor R62 622 and the condenser C64 628 can be calculated from the current wave form shown in FIG. 9b. 
If it is designed that the commercial power supplied to the rectifier circuit part 610 is 220V and the current required for the DC voltage generating part 620 is 20 mA, an average value of the current flowing through the resistor R62 622 is also 20 mA. Therefore, an electric power consumed by the resistor R62 622 is about 214V×20 mA, i.e., about 4.28 W.
If the electric power of about 4.28 W is unnecessarily consumed in order to generated the DC voltage required for the LED lighting apparatus, it is against the aim of the LED lighting apparatus, which reduces the power loss, and thus it is required to improve the problem.